1. Field
Embodiments of the present disclosure relate to a refrigerant recovery operation method for use in a refrigerator in which a freezing chamber and a refrigerating chamber are independently cooled.
2. Description of the Related Art
Generally, refrigerators are apparatuses to which a general refrigerating cycle to circulate a refrigerant thereinto is applied so as to supply cold air, generated by absorbing surrounding heat when the refrigerant in a liquid state is evaporated, to storage chambers, such as freezing and refrigerating chambers, to store food in a fresh state for a long time. The freezing chamber is kept at a low temperature of about −20° C., and the refrigerating chamber is kept at a low temperature of about 3° C.
Among these refrigerators, a parallel cycle-type refrigerator in which an evaporator is separately installed in each of a freezing chamber and a refrigerating chamber and operations of the freezing chamber and the refrigerating chamber are independently controlled using a 3-way valve has been disclosed.
The parallel cycle-type refrigerator achieves the operation of the refrigerating chamber independently of the operation of the freezing chamber and thus maintains high evaporation temperature of the refrigerating chamber, thereby improving energy efficiency during the operation of the refrigerating chamber. However, in the parallel cycle-type refrigerator, a certain amount of refrigerant moves to the freezing chamber evaporator and is trapped in the freezing chamber evaporator, and thereby the refrigerant becomes insufficient during the next operation of the refrigerating chamber.
Therefore, in the conventional parallel cycle-type refrigerator, after the operations of the refrigerating chamber and the freezing chamber, a refrigerant recovery operation (a pump down operation), in which the refrigerant distributed at a low-pressure part (the freezing chamber evaporator and the refrigerating chamber evaporator) is transferred to a high-pressure part (a condenser) by operating the compressor under the condition that passages of the 3-way valve in two directions, i.e., passages of the 3-way valves at the sides of the refrigerating chamber and the freezing chamber are closed, is performed, and then the operation of the compressor is completed.
Conventionally, the refrigerant recovery operation is performed only once when the compressor starts operation or just before the compressor stops operation. Therefore, the time for the refrigerant recovery operation must be sufficiently guaranteed so as to recover refrigerant kept at a low-pressure part. However, since suction pressure of the compressor is reduced in proportion to the increasing refrigerant recovery operation time, energy needed to drive the compressor increases and pressure of the low-pressure part (a freezing chamber evaporator and a refrigerating chamber evaporator) is rapidly reduced down to a vacuum. If a temperature of each evaporator is rapidly reduced to an extremely low temperature due to abrupt pressure reduction and refrigerant evaporation, refrigerant having an extremely low temperature is introduced into the compressor, such that the compressor temperature is reduced and liquid compression occurs, resulting in reduction of reliability of the compressor. As a result, there is a need to increase the refrigerant recovery amount within a predetermined pressure range in which the compressor can operate.